Contact allergens in moisturizers in preventative emollient therapy – A systematic review

BACKGROUND: Results of preventative emollient therapy on atopic dermatitis and food allergy trials are inconsistent. In addition to the ingredients considered beneficial, the moisturizers may contain potentially harmful haptens. This study aimed to assess the prevalence of haptens in moisturizers used in studies to prevent atopic dermatitis or food allergy and assess their correlations to the trial results. METHODS: A systematic search of studies investigating the role of emollient usage in preventing atopic dermatitis or food allergy in infants was performed from inception to December 2020. Haptens were identified based on the nine common patch test series (European, American, and Australian). RESULTS: 12 clinical trial studies were included in the review. In total, 16 different emollients were applied as an intervention. The vast majority (75%) of preparations contained at least one hapten from which several substances pose high allergic or irritant potential. Quantitative data synthesis of the findings regarding food allergy and atopic dermatitis prevention was not possible due to the significant heterogeneity of preparations used. CONCLUSIONS: Careful selection of emollient should consider the absence of potentially harmful ingredients, particularly when used in youngest children. Chronic skin exposure to haptens promotes the development of allergic contact dermatitis and moreover, via deterioration of the skin barrier and subclinical inflammation, may facilitate epicutaneous sensitization and promote atopic dermatitis; however further research is needed to validate our suppositions.